IE880545L - Sustained release matrix formulations - Google Patents

Abstract

This invention provides a matrix composition for sustained drug delivery which is comprised of an active agent, a hydrophilic polymer and an enteric polymer. The enteric polymer is impermeable to gastric fluids and aids in retarding drug release in regions of low pH, thus allowing lower levels of hydrophilic polymer to be employed. At the pH range of intestinal fluids, this polymer will dissolve and thereby increase the permeability of the dosage form. This approach is useful in sustaining the release of numerous active agents whose solubility declines as the pH is increased, a characteristic of weakly basic drugs. By responding to changes in physiological pH, these sustained release dosage forms have acceptable performance, in spite of variability in the gastrointestinal transit times of the formulation. [EP0280571A2]

Description

This invention relates to sustained release 5 pharmaceutical formulations, particularly those containing antimicrobial agents.

Ideally, a sustained release dosage form should deliver the medicament at a constant rate throughout the gastrointestinal tract. With many of the 10 delivery systems currently available, this expectation may not be realized since many drugs which are weakly acidic or basic exhibit solubility which varies in relation to pH. A decline in solubility in response to pH fluctuations within, the body may result in a 15 decreased release rate if the formulation does not respond with an appropriate change in its permeability characteristics - The use of hydrophilic matrices to provide sustained drug release is known. Christenson et al. in U.S. 20 Patent 3,065,143 disclose the use of certain hydrophilic gums, including hydroxypropyl methylcelluloses, in the preparation of sustained release tablets. Hill in U.S.

Patent 3,458,622 describes the preparation of sustained release tablets using a combination of povidone and carbopol. 25 Chem Abs 9|L 1983 no. 110763c describes a sustained release matrix containing a hydrophilic polymer and an enteric polymer. EP-A-142877 describes a sustained release matrix having an inert and a hydrophilic substance. GB-A-2067072 describes tablets containing a release-controlling agent and an erosion-30 promoting agent. US-A-4520009 describes constant-release aspirin tablets containing cellulose acetate phthalate and a plasticiser. Weiss et al■ in U.S. Patent Mo. 4,252,786 describe 6 '-419 -2- a controlled release tablet consisting of a core tablet which was identical to the tablet disclosed in Hill, that is, containing an active ingredient, povidone, and carbopol. A coating consisting of a hydrophobic and a 5 hydrophilic polymer was employed to prevent the initial burst of drug release encountered ^rith this tablet.

Schor et al. in U.S. Patent No, 4,389,393 describe sustained release therapeutic compositions based on high molecular weight hydroxypropyl methylcellulose. 10 Conventional hydrogels such as those based on high viscosity hydroxypropyl methylcelluloses are known to deliver medicaments at a constant rate independent of pH in relation to the hydration, gel viscosity and relative permeability of the dosage form. This, how-15 ever, does not ensure that a drug whose solubility varies significantly as a function of pH will be delivered at a constant rate throughout the gastrointestinal pH range. With these conventional hydrogel formulations, the rate of drug release will be directly related to the solu-20 bility of the drug. If the drug possesses greater solubility in gastric fluids as compared, to intestinal fluids, a characteristic of many weakly basic active ingredients, one would expect, the release rate of the matrix to be faster in gastric fluids, than when the 25 formulation makes the transition into the small intestine where the pE values are reported to be higher. For these formulations, if the dosage form is not retained for an adequate time period in the stomach, the decrease in drug release rate encountered in the intestine might 30 result in incomplete bioavailability and greater variability from patient to patient.

Film coatings are known, to have the ability to modify the release pattern of a drug once applied to pharmaceutical products. One type of film coating, known as an enteric coating, is used to prevent the release of drugs in, or protect drugs from, the effects of the gastric environment. Enteric coatings are used to delay the release of drugs which are inactivated by the stomach contents or which cause gastric irritation.

The matrix compositions of the present invention differ from existing formulations in that the present compositions have been designed to respond to increases in pH with a corresponding increase in the permeability of the dosage form. This allows the dosage form to release the active ingredient at an appropriate rate throughout the gastrointestinal tract.

This invention provides a matrix composition comprised of an active agent, a hydrophilic polymer, and an acrylic polymer which results in a dosage form which is responsive to physiological pH changes. More specifically, the present invention relates to a sustained release matrix formulation in tablet form comprising from about 0.1% by weight to about 90% by weight of an antimicrobial agent, from about 5% by weight to about 29% by weight of a hydrophilic polymer, and from about 0.5% by weight to about 25% by weight of an acrylic polymer, with the proviso- that the total weight of the hydrophilic polymer and acrylic polymer is less than 30% by weight of the formulation. This formulation, reacts to an increase in pH with a corresponding increase in its permeability and rate of erosion. This results in an improved mechanism for the sustained delivery of a variety of compounds, especially those whose solubility declines as the pH is increased.

Amounts and percentages are described herein as weight units unless otherwise stated.

The present formulation is in the form of a matrix of the ingredients comprising the formulation. A matrix, as defined herein, means a well-mixed composite of ingredients fixed into shape by tabletting. This intimate admixture of ingredients provides sustained release of the active agent contained therein as the pH of the environment changes following administration to a patient in need of such prolonged payout.

The percent of the ingredients required in the formulation of the invention, namely the active ingredient, the hydrophilic polymer, and the acrylic polymer, is calculated on a dry weight basis without reference to any water present. Thus? these three components together constitute 100 percent of the formulation for purposes of calculating individual percentages. If other ingredients are present, the sum of all of the components, with the exception of the film-coating, if any, consitutes 100 percent of the formulation for purposes of calculating individual percentages.

The antimicrobial agent will be present in a composition of the invention at a concentration in the range of about 0.1% by weight to about 90% by weight, more preferably at a concentration in the range of about 45% by weight to about 85% by weight. Typical medicaments which might benefit from this type of delivery system are antimicrobial agents such as cephalexin, cefaclor, cefadroxil, cefuroxime, cefuroxime axetil, erythromycin., penicillin, 7-[D~(aminophenylacetyl)amino]-3~chloro-8~ oxo~X~azahicyclo[4.2.0]oct-2-ene~2-carboxylic acid, also known as loracarbef, 7-[[amino(3-[(methylsulfonyl)amino]-phenyl]acetyl] amino]~3-chloro-8~oxo-l~azabicyclo[4.2.0]-oct-2-ene~2-carboxylic acid, and 7- [D-[amino[3-[(ethyl-sul f onyl) amino ] phenyl ] acetyl ] amino ] -3~chloro~8-oxo-l-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid.

Examples of agents for which this invention is particularly suited are cephalexin and cefaclor. Both compounds are zwitterions, possessing both an acidic and ~6~ a basic functional group. Both have greater solubility at the low pH values reported for gastric fluids (pH 1-3), than at the values normally reported for intestinal fluids (pH 5-7). When these compounds are placed, into 5 a conventional hydrogel, the release rate will be faster in simulated gastric fluids than when the formulation is exposed to simulated intestinal fluids.

The compositions of the present invention will also contain a hydrophilic polymer» Hydrophilic poly-10 raers will be present in the compositions of the invention at a concentration in the range of about 5% by weight to about 29% by weight, more preferably from about 5% by weight to about 20% by weight. Hydrophilic polymers suitable for use in this invention are either water 15 soluble or water swellable, and include one or more natural or partially or totally synthetic anionic or nonionic hydrophilic gums, modified cellulosic substances or proteinaceous substances such as acacia, gum tragacanth, locust bean gum, guar gum, karaya gum, agar, 20 pectin, carrageen, soluble and insoluble alginates, methylcellulose, hydroxypropyl methylcellulose, hydroxy-propyl cellulose, hydroxyethylcellulose, sodium carboxy-methylcellulose, carboxypolymethylene, gelatin, casein, sein, bentonite, magnesium aluminum silicate and the 25 like. Other hydrophilic polymers which could be employed include polysaccharides and modified starch derivatives such as Amazio 721A (American Maize Products) and Pullulan (Hayashibara Biochemical Laboratories, Inc.).

Preferred hydrophilic polymers are the hydroxy-30 propyl methylcelluloses manufactured by Dow Chemical and known as Methocel ethers. Preferred Methocel ethers include the Methocel E series gums (E 5, E 15, E 50, E4M, EXOM and the like). The hydration rate of the Methocel E series gums is typically slower than the hydration rate of the Methocel K series gums, when the Methocel E series gums are used to prepare hydrogel tablets, thinner gel layers will result. As a consequence, when these tablets are exposed to a media of higher pH, the tablets respond more quickly than when polymers which provide thick viscous gel layers are employed. Yet another preferred polymer is Fullulan, a water soluble polysaccharide which is derived from starch. Fullulan is similar to the Methocel E series gums in that hydrogel tablets containing Pullulan normally form thin gel layers, when employed in conventional hydrogel tablets, Pullulan has only moderate ability to retard drug release.

The formulations of the invention will also contain an acrylic polymer. These polymers will be present in the compositions of the invention at a concentration in the range of about 0.5% by weight to about 25% by weight, more preferably at a concentration in the range of about 1,5% by weight to about 15% by weight. The pH at which these polymers begin to dissolve will be in the range of about 5.0 to about 7,4. The polymers will be insoluble at a pH below about 5.0. Since these polymers are insoluble at the low pH values corresponding to gastric fluids, they aid. in retarding drug release in these regions. When exposed to fluids of higher pH, similar to those found in the small intestine, these -8» polymers will dissolve, and thereby increase the permeability and rate or erosion of tablets of the present invention. Examples of suitable polymers include acrylic resins such as Eudragit L, Eudragit S, Sudragit L-100-55^ Rohm Pharraa and acrylic latex dispersions, for example, Eudragit 1.30D- Rohm Pharma.

A preferred acrylic polymer is Eudragit L-100-55. This resin is available both as a fine powder or as an aqueous dispersion Eudragit L30D. This resin begins to dissolve above a pH of about 5.5, and for this reason aids in improving drug release over a major portion of the small intestine- The total concentration of the hydrophilic polymer and the acrylic polymer will be less than 30% by weight of the total formulation.

The present formulations may also contain a pharmaceutical^ acceptable binder at a concentration in the range of about 2.0% by weight to about 10.0% by weight, preferably from about 2.0% by weight to about 6.0% by weight. Pharmaceutically acceptable binders suitable for use in the present formulations are chosen from those routinely used, by formulation chemists and include sucrose, lactose, gelatin, starch paste, acacia, tragacanth, and other gums; cellulose derivatives such as methylcellulose, sodium carboxymethylcellulose, hydroxypropyl cellulose, hydroxypropyl methylcellulose, and ethylcellulose; microcrystalline cellulose; povidone; polyethylene glycols; com syrup; and other binders known to those familiar with pharmaceutical formulations. Preferred binders are Pullulan and hydroxypropyl cellulose.

The present formulations may also contain from about 2.0% to about 25.0% by weight of a pharmaceutically acceptable excipient, preferably from about 5% to 20% by weight. These excipients may be water soluble and should be chemically inert to the other ingredients. Preferable excipients would include lactose and mannitol. Alternatively, a variety of other known excipients could be employed such as glucose, fructose, xylose, galactose, sucrose, maltose, xylitol, sorbitol, as well as other pharmaceutically acceptable monosaccharides and disaccharides . Other suitable excipients would include inorganic compounds such as the chloride, sulfate and phosphate salts of potassium, sodium, and magnesium, as well as the calcium and succinate salts of citrate, phosphate, lactate and gluconate.

The present formulations may also contain a tablet lubricant. The lubricant will be present in the formulation at a concentration in the range of about 0.5% to about 4.0% by weight, preferably from about 1.0% to about 2.5% by weight. Preferred lubricants are stearic acid, in powder form„ and magnesium stearate. Other suitable tablet lubricants are calcium or zinc stearate, hydrogenated vegetable oils, talc, polyethylene glycols, mineral oil or other pharmaceutical^ acceptable die wall lubricants.

If desired, other conventional tablet ingredients such as preservatives, stabilizers, glidants, pharmaceutically acceptable surface active agents, and -10- FD&C colors may be included in the present formulations. The total weight of these ingredients is typically in the range of about 0.1% to about 2.0% of the weight of the formulation. Acceptable glidants or flow enhancers 5 include colloidal silicon dioxide and talc. Acceptable surface active agents include sodium lauryl sulfate, dioctyl sodium sulfosuccinate (DSS), triethanolamine, polyoxyethylene sorbitan and poloxalkol derivatives, quaternary ammonium salts or other pharmaceutical ly 10 acceptable surface active agents. Additionally, the lubricants and surface active agents can be combined and incorporated in the formulation as a single ingredient.

The resulting tablets may be coated, if desired, with one of many readily available coating 15 systems. Coating the tablets serves to mask the taste of the drug, make the tablet easier to swallow and, in some cases, improve the appearance of the the dosage form. The tablets can be sugar coated according to procedures well known in the art, or can be coated 20 with any one of numerous polymeric film coating agents frequently employed by formulation chemists. Representative examples of such film coating agents include hydroxypropyl methylcellulose, carboxymethylcellulose, hydroxypropyl cellulose, methylcellulose, ethylcellu-25 lose, acrylic resins, povidone, polyvinyl die thy1amino~ acetate, cellulose acetate phthalate, polyvinyl acetate phthalate, hydroxypropyl methylcellulose phthalate, acrylic latex emulsions, ethylcellulose latex emulsions or other commercially available preparations such as 30 Pharmacoat, manufactured by Shin-Etsu Chemical Co., Ltd, and opadry, manufactured by Colorcon, Inc. -11- The present formulations may be prepared by procedures well known to formulation chemists. The method of manufacturing can affect the release characteristics of the finished tablets. The acrylic polymer employed in the present formulations may be incorporated into the formulation in a number of ways. The polymer may be added as a finely divided powder to the active agent along with all or part of the hydrophilic polymer. These ingredients are thoroughly mixed and granulated with either water or an aqueous solution of the hydrophilic polymer or other binder. This granulation is dried and sized. The resulting granulation may be blended with additional hydrophilic polymer and tablet lubricants, and then compressed into tablets. This particular method of manufacture requires a larger percentage of enteric polymer to yield the desired balance of appropriate release in both simulated gastric fluids and simulated intestinal fluids, but eliminates the need for organic solvents during the manufacture of the tablets.

Alternatively, the acrylic polymer can be added as a finely divided, powder to the active agent and optionally all or part of the hydrophilic polymer. These ingredients are thoroughly mixed. Next, rather than using aqueous ingredients during the granulation step, organic solvents such as isopropyl alcohol, ethanol and the like may be employed with or without water. If desired? a suitable hydrophilic polymer can be dissolved in the solvent. Using this type of granulating fluid, the finely divided enteric polymer may -12- toeeome activated or partially dissolved during the granulation phase. In this state, it may be more effective in retarding drug release at low pH. This granulation is then processed as described above. This method of 5 incorporation may result in reduced requirements for both the enteric polymer and hydrophilic polymer, which may be a significant advantage when the active agent is very soluble or is to be employed at high doses.

A minor variation of the above method would 10 be to dissolve the acrylic polymer in an appropriate solvent system such as isopropyl alcohol, ethanol, and the like, with or without water. The resulting solution of the acrylic polymer is then, used to granulate the active agent which may optionally contain a portion 15 of the hydrophilic polymer. This method of incorporation allows the acrylic polymer to mora effectively retard drug release at low pH. The resulting granulation is then processed as described above. This processing method may again result in reduced requirements 20 for both the acrylic polysaer and hydrophilic polymer.

A third method for incorporation, of the acrylic polymer into a composition ox the invention requires using an aqueous latex dispersion of the polymer as the granulating fluid. In this instance, 25 the active agent and all or part of the hydrophilic polymer would be thoroughly mixed. The dispersion of the acrylic polymer is then added to complete the granulation. The resulting tablets have many of the properties of the solvent granulation tablets described 30 above, but this method does not require the use of these -13™ solvents. The aqueous dispersion, however, may not possess much tackiness, and the hydrophilic polymer which may be required to yield a suitable granulation by this method, may yield tablets which do not have the 5 desired release profile at high and low pH that can be achieved using other manufacturing procedures.

The method of incorporation of the hydrophilic polymer will also have an effect on the release rate of the resulting tablets. These effects are well known to 10 those familiar with hydrogel technology. It should be noted that when higher viscosity hydrophilic polymers are added to the formulation prior to wet granulation with aqueous solutions, the resulting tablets may have compromised release profilers when exposed, to media of 15 pH high enough to dissolve the enteric polymer.

As noted above, examples of agents for which this invention is particularly suited are cephalexin and cefaclor. When these compounds were placed into a conventional hydrogel composition, the release rate was 20 faster in simulated gastric fluids than when the formulation was exposed to simulated intestinal fluids. This characteristic is demonstrated by the following example; Example A 25 The following example is a cephalexin mono-hydrate sustained release tablet prepared using conventional hydrogel technology: "14- Per Tablet: Unit. Formula weight (mg) cephalexin povidone-90 Methocel B4M Premium stearic acid powder magnesium stearate 1074.5 mg 24.0 mg 161.3 mg 15.1 mg 15.1 mg 10 15 The release tendencies of these tablets were evaluated using two dissolution procedures. One procedure is termed the "gastric method" and. the other procedure is the "simulated GI method". According to the gastric method, the tablets were evaluated in 0.1 N hydrochloric acid which represents simulated gastric fluids. The simulated gastrointestinal (GI) method was designed to simulate gastrointestinal transit. According to the simulated GI method, the tablets were exposed for one hour to 750 ml of 0.1 N hydrochloric acid, at which time the pH in the dissolution kettle was increased to pH 6.8 by the addition of 250 ml of 0.2 H tribasic sodium phosphate. The dissolution results of these tablets are presented below: -15- Cephalexin Dissolved (Cumulative Percent) Time (minutes) Gastric Method Simulated GI Method 30 17 17 60 28 28 90 38 33 120 48 34 180 65 39 240 79 44 300 90 49 360 98 55 420 105 59 15 The tablets.were placed into a 10 mesh basket and were rotated in the above media at 100 rpm.

The dissolution data illustrates a potential problem with the use of conventional hydrogel technology with a compound whose solubility declines as the pH is 20 increased. With the above formulation, when the tablets were exposed to media of a higher pH in the simulated GI method, the release rate of cephalexin from the formulation declined dramatically. "«hen used clinically, this formulation may not perform as intended if the dosage 25 form does not remain in the stomach. Premature emptying of the tablet into the small intestine, and the resulting pH increase, could result in a decreased cephalexin release rate and poor bioavailability. These conditions would lead, to potential problems if they occurred, on a 30 continued basis, such as therapeutic failure in the treatment of some types of infection.

-IS- The following Examples illustrate the formula tions of the invention, and methods of for their prepa ration.

Example 1 A Hobart mixer was charged with 2149 g of cephalexin monohydrate. The resulting mixture was granulated with 1000 ml of 15% w/v Eudragit L-100-55 in a mixture of isopropyl alcohol:water (9:1, v:v).

Total granulating time was between five to seven minutes. The wet granulation was placed through a 4.75 mm [No. 4 mesh] screen onto paper-lined trays and dried at 35°C for five and one-half hours. Drying was continued at room temperature overnight. The dried granulation was placed through a 1.40 mm [Nb. 14 mash] screen into an appropriate container.

A v-blender was charged with 575 g of this granulation and 62.5 g of hydroxypropyl methylcellulose E-50 to prepare 500 tablets. This mixture was blended for about thirty minutes. To the mixture was added stearic acid, powder (7.5 g) and magnesium stearate (3.25 g) through a 600 pm [No. 30 mesh] screen. This material was mixed for five minutes and discharged into an appropriate container. The resulting mixture was compressed on a Stokes F-press tabletting machine using conventional tooling. -17- Per Tablet Unit Formula: 10 weight weight (mg) (percent) cephalexin monohydrate 1074.5 82.91 Eudragit L-100-55 75.0 5.79 hydroxypropyl methylcellulose E-50 125.0 9.65 stearic acid powder 15.0 1.15 magnesium stearate 6.5 0.50 The dissolution of these tablets v?as evaluated by the previously described methods with the following results: 15 Cephalexin Dissolved (Cumulative Percent) Time (minutes) Gastric Method Simulated GI Method 30 22 20 SO 35 32 90 45 40 120 53 50 180 66 69 240 77 84 300 85 92 360 94 93 420 100 93 -18- Example 2 A Hobart mixer was charged, with 1612 g of cephalexin monohydrate, 300 g of Eudragit L-100-55 and 5 225 g of hydroxypropyl methylcellulose E-5 through an appropriate screen. The mixture was blended thoroughly and granulated with 750 ml of an 8% w/v hydroxypropyl methylcellulose E-5 solution in a mixture of isopropvl alcohol and water (3s7, v;v). Total granulating time 10 was between five and ten minutes. The wet granulation was placed through a 4.75 mm [No. 4 mesh] screen onto paper-lined trays and dried at 45°C for one half hour. Drying continued at room temperature for 48 hours. The dried granulation was placed through a 1.40 mm [Wo. 14 mesh] screen into an appro-15 priate container.

A v-blender was charged with 732 g of this granulation followed by 11 g of stearic acid powder and 7.77 g of magnesium stearate were added through a600 urn [No. 30 mesh] screen. This material was mixed for five minutes 20 and discharged into an appropriate container. The resulting mixture was compressed on a Stokes F-press tabletting machine using conventional tooling.

The resulting tablets were film coated with a solvent based film coating mixture consisting of hydroxy-25 propyl methylcellulose E-50 (1.581 weight percent) and glycerin (0.552 weight percent) in a conventional coating pan. The tablets were then placed onto paper-lined trays to dry to provide approximately 1000 tablets.

I -19- Per Tablet Unit Formula; weight weight (mg) (percent) cephalexin monohydrate 537, .23 71, ,54 Eudragit L-100-55 100, .00 13, ,32 hydroxypropyl methylcellulose E-5 95, .00 12. .65 stearic acid powder 11. .00 1. ,46 magnesium stearate 7. .77 1. .03 clear film coat (theory) 15, .88 10 The dissolution of these tablets was evaluated by the previously described methods with the following results: 15 Cephalexin Dissolved (Cumulative Percent) Time (minutes) Gastric Method simulated GI Method 30 28 21 60 48 46 90 65 60 120 82 73 180 100 93 240 100 99 25 Example 3 A pony mixer was charged with 3224 g of cephalexin monohydrate, 300 g of Eudragit L-100-55 and 30 93 g of hydroxypropyl cellulose L.F. through an appropriate screen. The mixture was blended thoroughly and. -20- granulated with 1200 ml of a 6% v/v aqueous hydroxy-propyl cellulose L.P. solution. Purified water was added in a quantity sufficient to produce a satisfactory granulation. Total granulating time was between five and ten minutes. The wet granulation was placed through a 4/75 ran [Wo. 4 mesh] screen onto paper-lined trays and dried at 35°C for 20 1/2 hours. The dried granulation was placed through a 1.70 inm [No. 12 mesh] screen into an appropriate container .

To prepare 1000 tablets, a v-blender was -charged with 1230 g of this granulation, and 100 g Methocel E4H CR grade was added through a 600 pm [No. 30 mesh] screen. This mixture was blended for about 20 minutes, after which 15 g stearic acid powder and 10.5 g magnesium stearate were added through a 600 urn [Nb. 30 mesh] screen. This material was mixed for five minutes and discharged into an appropriate container. The resulting mixture was compressed on a Stokes F-press tab letting machine using conventional tooling.

The resulting tablets were film coated with a solvent based film coating mixture consisting of hydroxy-propyl methylcellulose E-50 (1.581 weight percent) and glycerin (0.552 weight percent) in a conventional coating pan. The tablets were placed onto paper-lined trays to dry. -21- Per Tablet Unit Formula: weight weight (mg) (percent) cephalexin monohydrate 1074 .50 79 .30 Eudragit L-100-55 100 .00 7 .38 hydroxypropyl cellulose L.F. 55 .00 4 „ 06 Methocel E4M CR grade 100 .00 7 .38 stearic acid powder 15 .00 1 . 11 magnesium stearate 10 .50 0 .77 clear film coat (theory) 50 .54 The dissolution of these tablets was evaluated by the previously described methods to provide the fol-15 lowing results: Cephalexin Dissolved (Cumulative Percent) Time (minutes) Gastric Method Simulated GI Method 30 12 12 60 31 30 90 47 37 120 60 180 80 58 240 93 72 300 99 82 360 103 89 420 105 93 -22- Example 4 A Hobart mixer was charged with 1612 g of cephalexin monohydrate and 45 g of hydroxypropyl cellulose L.F. through an appropriate screen. This mixture was blended thoroughly and granulated wi tli 500 ml of an aqueous dispersion Eudragit L30D (equivalent to 150 g Eudragit L-100-55). Purified water was added in a quantity sufficient to produce a satisfactory granulation. Total granulating time was between five and ten minutes. The wet granulation was placed through a 4.75 mm [No. 4 mesh] screen onto paper-lined trays and dried at 35°C for 20 hours. The dried granulation was placed through a 1.40 mm [Mo. 14 mesh]screen into an appropriate container.

To prepare 500 tablets, a v-blender was charged with 602 g of this granulation and 50 g of Methocel E4H CR grade was added through a 600 (jm [No, 30 mesh] screen. This mixture was blended for about 20 minutes, after 'which 7.5 g of stearic acid powder and 5.25 g magnesium stearate were added through a 600 pm [No. 30 mesh] screen. This material was mixed for five minutes and discharged into an appropriate container. The resulting mixture was compressed on a Stokes F-press tabletting machine using conventional tooling.

Per Tablet Unit Formula: weight weight -JmL. (percent) cephalexin monohydrate 1074. 50 80 .79 Eudragit L30D (solids) 100. 00 7 .52 hydroxypropyl cellulose L.F. 30. 00 2 .26 Methocel E4M CE grade 100. 00 7 .52 stearic acid powder 15. 00 1 .13 magnesium stearate 10. 50 0 .78 -23" The dissolution of these tablets was evaluated by the previously described methods to give the follow ing results: 5 Cephalexin Dissolved (Cumulative Percent) Time (minutes) Gastric Method Simulated GI Method 30 22 21 60 33 32 10 90 42 37 120 50 39 180 S3 49 240 75 S7 300 85 79 15 360 93 85 420 97 88 Example 5 20 A Hobart mixer was charged with 2149 g of cephalexin monohydrate. This material was granulated with 1000 ml of a 10% w/v Eudragit L-100-55 in a mixture of isopropyl alcohol and water (9:1, v:v). Total 25 granulating time was about seven minutes. The wet granulation was placed through a 4.75 ram [No. 4 mesh] screen onto paper-lined trays and. dried at 35°C for two hours.

Drying was continued, at room temperature overnight. The dried granulation was placed through a 1.40 ram [No. 14 mash] 30 screen into an appropriate container. -24- To prepare 300 tablets, a v-blender was charged with 337 g of the granulation and 45 g of hydroxypropyl methylcellulose £-50. This mixture was blended for about thirty minutes. Stearic acid powder (4.5 g) and mag-5 nesium stearate (1.95 g) were added to the mixture through a 600 pm [Mo„ 30 mesh] screen. This material was mixed for five minutes and discharged into an appropriate container. The resulting mixture was compressed on a Stokes F-press tabletting machine using conventional 10 tooling.

Per Tablet Unit Formula: weight weight (mg) (percent) cephalexin monohydrate 1074.5 82.91 15 Eudragit L-100-55 50.0 3.86 hydroxypropyl methylcellulose E-50 150.0 11.57 stearic acid powder 15.0 1.16 magnesium stearate 6.5 0.50 The dissolution of these tablets was evaluated by the previously described methods with the following results: Cephalexin Dissolved (Cumulative Percent) 25 Time (minutes) Gastric Method Simulated GI Method 30 24 24 60 38 37 90 47 46 30 120 54 55 180 73 76 240 94 89 300 99 94 -25- Example 6 A Hobart mixer was charged with 500 g of cefaclor monohydrate, 55 g of lactose and 100 g of 5 hydroxypropyl methylcellulose E-5 through an appropriate screen. The mixture was blended thoroughly and granulated with 350 ml of a 5% w/v Eudragit L-100-55 solution in a mixture of isopropyl alcohol and water (19:1, v:v). Total granulating time was between five and ten minutes. 10 The wet granulation was placed through a 4.75 irni [No. 4 mesh] screen onto paper-lined trays and dried at 50°C for one hour. Drying continued at room temperature for 48 hours. The dried granulation was passed through a 1.18 ram [No. 16 mesh] screen into an appropriate container. 15 To prepare 500 tablets, a v-blender was charged with 268 g of the granulation, and 3.75 g of stearic acid powder and 2.5 g of magnesium stearate were added through,a 600 pm [No. 30 mesh] screen. The resulting mixture was mixed for five minutes and discharged into an 20 appropriate container. The resulting mixture was compressed on a Stokes F-press tabletting machine using conventional tooling.

Per Tablet Unit Formula: weight weight 25 (rag) (percent) cefaclor monohydrate 392.30 71.50 lactose 50.98 9.30 Eudragit L-100-55 13.71 2.50 hydroxypropyl methylcellulose E-5 78.45 14.32 30 stearic acid powder 7.50 1.37 magnesium stearate 5.00 0.91 -26- The dissolution of these tablets was evaluated by the previously described methods with the following results; 5 Cefaclor Dissolved (Cumulative Percent) Time (minutes) Gastric Method Simulated GI Method 30 22 23 60 33 32 10 90 41 54 120 47 07 180 61 112 240 75 300 85 15 360 92 420 97 Example 7 20 A Hobart miser was charged with 500 g of cefaclor monohydrate, 40 g of Eudragit L-100-55, 50 g of lactose and 75 g of Fullulan PI-20 through an appropriate screen. The mixture was blended thoroughly and 25 granulated with 200 ml of a 5% w/v hydroxypropyl cellulose L.F. solution in a mixture of is ©propyl alcohol and water (19:1, v:v). Total granulating time was between five and ten minutes. The wet granulation was placed through a 4»75 iron [No. 4 mesh] screen onto paper-lined trays and then 30 dried at 50°C for two hours. Drying continued at room -21" temperature for 24 hours. The dried granulation was placed through a 1 ..40 mm [No. 14 mesh] screen into an appropriate container. h v-blender was charged with 266 g of the 5 granulation, and 3.75 g stearic acid powder and 2.5 g of magnesium stearate were added to the blender through a 600 pin [No. 30 mesh] screen. This material was mixed for five minutes and discharged into an appropriate container. The resulting mixture was compressed on a Stokes F-press 10 t&hletting machine using conventional tooling to provide 500 tablets.

Per Tablet Unit Formula; weight weight (m g) (percent) cefaclor monohydrate 392 .30 73 .43 lactose 39 .23 7 .34 Eudragit L-100-55 31 .36 5 .87 Pullulan PI-20 58 .85 11 .02 stearic acid powder 7 .50 1 .40 magnesium stearate 5 .00 0 .94 -28- Tfee dissolution of these tablets was evaluated by the previously described methods to afford the follow ing results: 5 Cefaclor Dissolved (Cumulative Percent) Time (minutes) Gastric Method 30 18 60 24 90 30 120 34 180 44 240 50 300 56 360 61 • 420 66 Example 8 20 A Hobart mixer was charged with 1177 g of cefaclor monohydrate, 212 g of mannitol and 176 g of hydroxypropyl methylcellulose E-5 through an appropriate screen. The mixture was blended thoroughly and granu-25 lated with 720 ml of a 5% w/v Eudragit L-100-55 solution in a mixture of isopropyl alcohol and water (9:1, v:v).

Total granulating time was five minutes. The wet granulation was placed through a 4.75 rran [No. 4 mesh} screen onto paper-lined trays and dried at 40°C for three hours. Drying con-30 tinued at room temperature overnight. The dried granulation was placed through a 1.18 mm [No, 16 mesh] screen into an appropriate container. -29™ To prepare 1500 tablets, a v-blender was charged with 800 g of this granulation. Stearic acid powder (11.25 g) and magnesium stearate (7.5 g) we re-added to the blender through a 600 |im [No. 30 mesh] screen. 5 The resulting material was mixed for five minutes and discharged into an appropriate container. The resulting mixture was compressed on a Stokes F-press tatoletting machine using conventional tooling. 10 Per Tablet Unit Formula: mq/tablet %v/w cefaclor monohydrate 392 .30 71 .83 mannitol 70 .70 12 .95 hydroxypropyl methylcellulose E-5 58 .50 10 .71 Eudragit L-100-55 12 .00 2 .20 stearic acid powder 7 .50 1 .37 magnesium stearate 5 .00 0 .94 20 The dissolution of these taJblets was evaluated by the previously described methods with the following results: -30- Cefaclor Dissolved (Cumulative Percent) Time (minutes) Gastric Method Simulated GI Method 30 20 21 5 60 31 30 90 38 61 120 46 111 180 63 240 79 10 300 91 360 98 420 103 15 . Example 9 A Hobart mixer was charged with 1177 g of cefaclor monohydrate, 212 g of mannitol and 176 g of hydroxypropyl methylcellulose E-5 through an appropriate 20 screen. The mixture was blended thoroughly and then granulated with 720 ml of a 5% w/v Eudragit L-100-55 solution in a mixture of isopropyl alcohol and water (9:1, v:v). Total granulating time was about five minutes-.- The wet granulation was placed through a 4.75 ran [No. 4 mesh] 25 screen onto paper-lined trays and dried at 40°C for three hours. Drying continued at room temperature overnight. The dried granulation was placed through a 1,18 mm [No. 16 mesh] screen into an appropriate container- -3I~ To prepare 1100 tablets, a v-blender was charged with 587 g of this granulation and 26.4 g of mannitol. This mixture was blended for about thirty minutes and combined with stearic acid powder (8.25 g) 5 and magnesium stearate (5.5 g) through a 600 pm [No. 30 mesh] screen. This material was mixed for five minutes and discharged into an. appropriate container. The resulting mixture was compressed on a Stokes F-press tabletting machine using conventional tooling. The resulting 10 tablets were film coated with a solvent based film coating mixture consisting of hydroxypropyl methylcellulose E-50 (1.55 weight percent), glycerin (0.54 weight percent) and Opaspray Blue (solids - 0.75 weight percent) in a conventional coating pan. The tablets were then placed 15 onto paper-lined trays to dry. 20 Per Tablet Unit Formula: weight weight (mq) (percent) cefaclor monohydrate 392.30 68.82 mannitol 94.70 16.61 hydroxypropyl methylcellulose E-5 58.50 10.25 Eudragit L-100-55 12.00 2.11 stearic acid powder 7.50 1.32 25 magnesium stearate 5.00 0.88 color film coating (theory) 13.01 -32- The dissolution of these tablets was evaluated hv the previously described methods with the following results: 5 Cefaclor Dissolved (Cumulative Percent) Time (minutes) Gastric Method Simulated GI Hethod 30 18 18 60 28 28 10 90 36 53 120 46 95 180 66 240 83 300 93 15 • 360 97 Example 10 20 A Hobart mixer was charged with 1569 g of cefaclor monohydrate, 201 g of mannitol and 264 g of hydroxypropyl methylcellulose E-5 through an appropriate screen. The mixture was blended thoroughly and granulated with 960 ml of a 5% w/v Eudragit L-100-55 solution 25 in a mixture of isopropyl alcohol and water (9:1, v:v). Total granulating time was about six minutes. The wet granulation was placed through a 4.75 mm [No- 4 mesh] screen onto paper~lined trays and dried at 28°C for six hours.

Drying continued at room temperature overnight. The 30 dried granulation was passed through a 1.18 mm [Nb. 16 mesh] screen into an appropriate container. l] -33- To prepare 1500 tablets, a v-blender was charged with 781 g of the granulation, 11.25 g of stearic acid powder and 7,,5 g of magnesium stearate. The lubricants were added through a 600 pm [Nb. 30 mesh] screen. 5 This material was mixed for five minutes and discharged into an appropriate container. The resulting mixture was then compressed on a Stokes F-press tabletting machine using conventional tooling. The resulting tablets were film coated with a solvent based film coat-10 ing mixture consisting of hydroxypropyl methylcellulose E-50 (1.55 weight percent), glycerin (0.54 weight percent) and Opaspray Blue (solids - 0.75 weight percent) in a conventional coating pan. The tablets were then placed onto paper-lined trays to dry. 15 Per Tablet Unit Formula: weight weight (met) (percent) 20 cefaclor monohydrate 3S2.30 73.60 mannitol o M O in 9.42 hydroxypropyl methylcellulose E~5 66.00 12.38 Eudragit L-100-55 12.00 2.25 stearic acid powder 7.50 1.41 25 magnesium stearate 5.00 0.94 color film coating (theory) 12.87 -34- The dissolution of these tablets was evaluated by the previously described methods with the following results? 5 Cefaclor Dissolved (Cumulative Percent) Time (minutes) Gastric Method Simulated GI Method 30 17 17 60 26 26 90 33 45 120 38 82 180 49 240 58 300 67 . 360 76 420 83 Example 11 20 A Hobart. mixer was charged with 1046 g of cefaclor monohydrate, 80 g of mannitol and 70 g of hydroxypropyl methylcellulose E-S through an appropriate screen. The mixture was blended thoroughly and then granulated with 500 ml of a 3% w/v Eudragit L-100-55 25 and 2.6% w/v hydroxypropyl cellulose EF solution in a mixture of isopropyl alcohol and water (isopropyl alcohol 90 parts : 10 parts water). Total granulating time was between three and four minutes. The wet granulation was placed through a 4.75 mm [No. 4 mesh] screen onto 30 paper-lined trays and then dried at 40° C for five hours. Drying continued at room temperature for -35- 24 hours. The dried granulation was placed through a 1.18 )jm [Nb. 16 mesh] screen and the granulation was returned to paper-lined trays and dried at 40° C for 2 1/2 hours to remove residual solvent.

To prepare 900 tablets, a v-blender was charged, with 550.8 g of this granulation. To this, 61.2 g of hydroxypropyl methylcellulose E-50 was added through a 600 |jm [No. 30 iresh] screen. The mixture was blended for twenty minutes in a v-blender. To this mixture, the lubricants stearic acid powder (6.3 g) and magnesium stearate (2.7 g) were added through a 600 pia [No. 30 mesh] screen. This material was mixed for five minutes and discharged into an appropriate container. The resulting mixture was then compressed on. a Stokes F-press tablet-ing machine using conventional tooling.

The tablets were film coated with a solvent based film coating mixture consisting of hydroxypropyl methylcellulose E«5Q (1.581 weight percent), glycerin 0.552 (weight percent) and Opaspray Blue (1.961 weight percent) in a conventional coating pan. The tablets were placed onto paper-lined trays to air dry. -36- Per Tablet Unit Formula: weight (mq) weight (percen cefaclor monohydrate 523.00 75.80 5 mannitol 40.20 5.80 hydroxypropyl methylcellulose E-5 35.00 5.07 Eudragit L-100-55 7.50 1.09 hydroxypropyl cellulose EF 6.50 0.94 hydroxypropyl methylcellulose E-50 68.00 9.86 10 stearic acid powder 7.00 1.01 aiagnesium stearate 3.00 0.43 blue film coating (theory) 12.50 The dissolution of these tablets was evaluated 15 by the previously described methods with the following results: Cefaclor Dissolved (Cumulative Percent) Time 20 (minutes) Gastric Method Simulated GI Method 30 16 17 60 30 34 90 44 56 120 57 71 25 180 81 88 240 101 100 -37- Examiole 12 To prepare 40 tablets, the following ingredients were passed through a 600 pm (No. 30 mesh) screen and 5 mixed together in a mortar and pestle- 8.44 g of 7-[D-(amixiophenylacetyl)amino]-3~chloro-8~oxo~l~asabi~ cyclo[4.2.0]oct~2-ene-2-carhoxylic acid monohydrate, 0.84 g of Eudragit L-100-55, and. 2.56 g of hydroxypropyl methylcellulose E-50. To this mixture, 0.104 g of 10 magnesium stearate and 0.216 g of talc were added and blended thoroughly. The resulting mixture was then compressed on a Stokes F-press tahleting machine using conventional tooling. 15 Per Tablet Unit Formula: weight weight (mg) (percent) 7-[D~(aminophenylacetyl)amino]-20 3-chloro~8-oxo-l-a£abicyclo- [4.2.0]oct-2-ene-2-carboxylic acid monohydrate Eudragit L-100-55 hydroxypropyl methylcellulose E-50 211.00 21.00 64.00 69.41 6.91 21.05 0.86 25 magnesium stearate talc 2.60 5.40 1.78 The dissolution of these tablets was evaluated by the previously described methods with the following results: -38- Active Agent: Dissolved (Cumulative Percent) Time (minutes) Gastric Method Simulated GI Method 30 23 24 5 60 43 44 90 65 59 120 80 68 150 92 79 180 100 87 10 240 105 99 300 104 105 Example 13 15 To prepare 40 tablets, the following ingre dients were passed through a 600 nm (No. 30 mesh) screen and mixed together in a mortar and pestle- 8.0 g of 7-[ [ amino [ 3 - [ (methylsulfonyl) amino ] phenyl ] acetyl ] amino ] -3 ~ c h 1 o r o ~ 8 ~ o x o -1 ~ a a a.b i cy c 1 o [4.2.0 ] oc t-2 - ene - 2 - carboxy 1 i c 20 acid, 0.8 g of Eudragit L-100~55, 1.6 g of hydroxypropyl methylcellulose E-50, and 0.96 g of Methocel E4M CR grade. To this mixture, 0.120 g of magnesium stearate and 0.200 g of talc were added and blended thoroughly. The resulting mixture was then compressed on a Stokes 25 F-press tablating machine using conventional tooling. -39- Per Tablet. Unit Formula: 10 7-[[amino[3-[(methylsulfonvl)-amino]phenyl]acetyl]amino]-3-chloro-S-oxo-l-asabicyclo[4.2.0]-oct-2~ene-2-carboxylic acid Eudragit L-100-55 hydroxypropyl Methylcellulose E-50 Methocel E4M CR grade magnesium stearate talc weight weight (mg) (percent) 200.00 20.00 40.00 24.00 3.00 5.00 58.49 6 .85 13.70 8.22 1.03 1.71 15 .The dissolution of these tablets was evaluated by the previously described methods with the followincr results: Active &qent Dissolved (Cumulative Percent) 20 Time (minutes) Gastric Method Simulated ' 30 19 18 60 29 28 90 40 36 25 120 50 40 150 58 43 180 65 48 240 78 58 300 89 69 30 360 97 78 420 100 84 -40- Examole 14 To prepare 40 tablets, the following ingredients were passed through a 600 pm (No. 30 mesh) screen and 5 mixed together in a mortar and pestle- 8.0 g of 7- [D-[amino[3-[(ethyl-sulfonyl)amino]phenyl]acetyl] amino]-3™chloro-8-oxo~l-a2sabicyclo[4.2.0]oct-2-ene-2-carboxylic acid, 0.8 g of Eudragit L-100-55, 1.6 g of hydroxypropyl methylcellulose E-50, and 1.0 g of Methocel E4M CR 10 grade. To this mixture, 0.20 g of magnesium stearate and 0.200 g of talc were added and blended thoroughly. The resulting mixture was then compressed on a Stokes F-press tableting machine using conventional tooling. 15 Per Tablet Unit Formula: weight weight (mg) (percent) 7~[D~[amino[3-[{ethyIsulfony1)- 20 amino]phenyl]acetyl]amino]-3- chloro-8-oxo-l-azabicyclo[4.2.0]- oct-2-ene-2-carboxylic acid Eudragit L-100-55 hydroxypropyl methylcellulose E-50 200.00 20.00 40.00 67.80 6.78 13.56 25 Methocel E4H CR grade aagnesium stearate 25.00 8.47 talc 5.00 5.00 1.69 1.69 -41- The dissolution of these tablets was evaluated by the previously described, methods with the following results: Active Agent Dissolved (Cumulative Percent) 5 Time (minutes) Gastric Method Simulated GI Method 30 18 17 60 27 28 90 34 35 120 43 39 150 50 42 180 56 47 240 67 56 300 76 65 360 86 75 420 92 84

Claims (1)

-42- OAIMS

1. A sustained release matrix fonnulation ia tablet form comprising fro® 0.1% by weight to 90% by weight 5 of as antimicrobial agent selected from cephalexin, cefaclor, cefadroxil, cefuroxime, cefuroxime axetil, erythromycin, penicillin,, loracarbef, 7- E [amino- [3-[ (methylsulfonyl) amino! -phenyl] acetyl] amino J -3-